Modern vehicles increasingly are equipped with advanced driver assistance systems (ADAS).
ADAS enable vehicle features such as automated lighting, adaptive cruise control, automatic breaking, collision warnings, proximity warnings, traffic and road condition warnings, connectivity with smartphones, lane keep assist, blind spot monitoring, and automated driving modes. In addition to being used for driver comfort and assistance, these systems may be used for collision avoidance to increase safety. For example, if a driver fails to respond to a proximity warning, automatic braking may allow the vehicle to stop on its own, avoiding a potential collision. Automated driving may function so as to steer the vehicle around dangers, or to steer the vehicle back into its lane if the driver begins to drift out of the lane.
ADAS rely on inputs from multiple data sources, including automotive imaging, light detection and ranging, radar, image processing, computer vision, and in-car networking. Additional inputs are possible from other sources separate from the primary vehicle platform, such as other vehicles (referred to as vehicle-to-vehicle systems) or from infrastructure such as cellular data or wireless internet systems (referred to as vehicle-to-infrastructure systems).
A primary sensor for many ADAS systems is an image sensor. As ADAS systems have progressed from driver assistance to include the automation and safety functions discussed above, the safe operation of the vehicle will depend more and more on the reliability of the image sensor and imaging system. Therefore, the reliable operation of the image sensor has become a critical safety component in many modern vehicles.
As a consequence, the ISO 26262 standard was developed to include the Automotive Safety Integrity Level (ASIL) risk classification scheme. The ASIL levels range from the lowest, ASIL-A (lowest), to ASIL-D (highest). An ASIL level is determined by three factors, namely the severity of a failure, the probability of a failure occurring, and the ability for the effect of the failure to be controlled.
Faults in semiconductor devices, such as image sensors, may arise from a number of causes including cosmic radiation, electromigration, early mortality, and a host of other reasons. Due to the importance of the operation of an image sensor in an ADAS system, is therefore desired to detect faults in the operation of an image sensor in an ADAS system as quickly as possible and as accurately as possible.